Clot Retrieval Device Using Inverted Collapse Mechanism
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Solution Overview
Problem
Current clot retrieval devices cause shearing and fracturing of clots during expansion, leading to increased risk of distal embolization and vessel injury, and require multiple passes which can result in additional complications.
Innovation Solution
A clot retrieval assembly with a retrieval device that transitions from an unexpanded state to an expanded state by bending elongate clot capturing elements, which are made from a shape memory alloy, reducing the need for axial force and minimizing vessel injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radially expandable retriever devices are used to capture clots, then clot capture capability is improved, but shearing and fracturing of the thrombus occurs leading to distal embolization
Solution Approach 1:
The patent inverts the traditional expansion mechanism by using a collapsible filter design that collapses onto the clot rather than expanding into it. The filter is delivered in an expanded state, positioned around the clot, and then collapsed to capture the thrombus, reversing the conventional approach of expanding into the clot and causing shearing forces.
Solution Approach 2:
The filter elements are constructed from flexible materials that can conform to the clot surface and adapt to vessel geometry. This flexibility allows the filter to capture clots without rigid structural interference, reducing shearing and fracturing while maintaining effective thrombus entrapment.
2Reliability
If multiple passes of the retriever device are performed to remove thrombus, then complete thrombus removal is achieved, but vessel injury such as dissection, perforation, or vasospasm increases
Solution Approach 1:
The filter is deployed in an expanded state before contact with the clot, allowing it to establish a secure position around the thrombus. This preliminary positioning enables subsequent collapse and capture in a single pass, eliminating the need for repeated device manipulations that cause vessel injury.
Solution Approach 2:
The patent replaces the traditional mechanical expansion-contraction mechanism with a collapse-based capture system. Instead of expanding into the clot and requiring withdrawal, the filter collapses onto the thrombus to capture it, reducing the number of passes needed and minimizing mechanical trauma to the vessel wall.
3Reliability
If axial force is applied to expand the retrieval device, then the device expands to capture the clot, but vessel injury and discomfort to the patient increases
Solution Approach 1:
Instead of applying axial force to expand the device, the patent applies force to collapse the pre-deployed expanded filter onto the clot. This inversion of the expansion-collapse sequence eliminates the need for axial expansion forces that can injure the vessel wall.
Solution Approach 2:
The filter dynamically transitions from an expanded delivery state to a collapsed capture state. This dynamic configuration change allows the device to adapt to the clot without requiring high axial expansion forces, reducing vessel injury while maintaining effective thrombus capture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The assembly effectively captures clots with reduced risk of distal embolization and vessel injury, and requires fewer passes, improving the safety and efficiency of clot removal.
Implementation Method 1
This radial force is through thermally-induced, martensitic transformation of the Nitinol elements of the device by a predetermined shape change in the geometry of the Nitinol.
Data Source
AI summary
Retrieval assemblies configured to capture an obstruction located in a bodily duct of a patient are provided. According to one implementation a retrieval assembly is provided that includes a distal collar operatively coupled to an elongate wire, a proximal collar slideable along a portion of the length of the elongate wire, and a plurality of circumferentially spaced-apart elongate clot capturing elements that each has a proximal end coupled to the proximal collar and a distal end coupled to the distal collar. The assembly being configured such that when the elongate wire is withdrawn proximally, the retrieval device transitions towards a fully expanded state.